The Findings (2 of 2)

3. Hormonal
effects: Both NK603 maize and Roundup significantly
and independently disrupted hormonal regulation. Substances that do this are
known as endocrine disruptors. Published evidence was cited to suggest possible
avenues through which this might happen.

The GM trait inserted into NK603
intentionally over-expresses a key enzyme which would otherwise be suppressed
by glyphosate. The GM version of the enzyme is unaffected by glyphosate,
meaning that the GM plant can survive despite being sprayed with glyphosate
herbicide.

However, in its original, unmodified state, this enzyme catalyzes
the first step in the shikimic acid pathway, a major metabolic trunk with many
outcomes. One of those outcomes is the production of the metabolites, caffeic
and ferulic acids, which may inhibit the growth of tumours. Ferulic acid is
also known to modulate estrogenic activity in mammals. Most mammary tumours are
known to be estrogen-responsive. The reduced levels of caffeic and ferulic acid
found in GM NK603 maize in this study would be consistent with the observed trends in
tumour occurrence, and specifically, with increased incidence of mammary
tumours.

In
addition to possible downstream metabolic impacts from the GM trait, it is also
necessary to account for the independent effect of glyphosate. Roundup, which
may be present as a residue in the sprayed GM maize treatments as well as in
the dosed water treatments, is known to disrupt aromatase. This pivotal enzyme,
also known as estrogen synthetase, catalyzes the conversion of androgen to
estrogen. Roundup has further been shown to impact upon androgen and estrogen
receptors, and to act as an endocrine disruptor of sex hormones (see evidence cited
in the Séralini study). Furthermore, glyphosate has been shown to act as an
estrogen substitute capable of stimulating the growth of estrogen-dependent
breast cancer cells at very low doses.[1] This may be a contributing factor to
the more rapid growth of mammary tumours in at least the Roundup treatment
groups.

Thus both the GM maize and the Roundup
herbicide it relies upon had toxic effects on the mammalian physiology in a
gender-specific way. In other words, the effects on males were different from
the effects on females.

Treatment responses recorded in this study
were nonlinear, meaning that the effect did not increase in proportion to the
dose. They appeared to be more reflective of a threshold-type response. For
example, incidence of NRPT in female rats was uniform across all three doses of
Roundup in drinking water. This would suggest that even the lowest dose was
high enough to meet the threshold for a full response. Endocrine disruptor
effects can act at extremely low concentrations and can be nonlinear.[2]
This may explain why in the present study, mortality appeared to be higher in
male rats fed a diet containing 11% GM maize than a diet containing 22% or 33%
GM maize.

The findings of the study challenge the
central premise of GM, namely that it is feasible to insert a transgene to
confer a single specific trait without compromising the expression of other
apparently unrelated traits.